Opera 21 is too problematic with my computer

ever since my computer has upgraded to Opera 21, i notice on the task manager that the memory and private memory for some tabs of the browser are higher then the actual browser process and it really high on a GIF heavy website and not to mention, issue i'm having with some pages going completely white while trying to scroll down on the page. it happened to me a lot in Chrome after they rolled out 34.0 hence why i'm using Opera now.

Sounds to me that computer is barely able to run Vista let alone any browser, you can speed that computer up a little by going into Msconfig, and shutting off everything except the Firewall and the Antivirus, Install Ccleaner and run it and then do a defrag and then reboot